Ae-Kyoung Lee

Bio: Ae-Kyoung Lee is an academic researcher from Electronics and Telecommunications Research Institute. The author has contributed to research in topics: Imaging phantom & Specific absorption rate. The author has an hindex of 14, co-authored 64 publications receiving 736 citations.

Comparisons of computed mobile phone induced SAR in the SAM phantom to that in anatomically correct models of the human head

Abstract: The specific absorption rates (SAR) determined computationally in the specific anthropomorphic mannequin (SAM) and anatomically correct models of the human head when exposed to a mobile phone model are compared as part of a study organized by IEEE Standards Coordinating Committee 34, Sub-Committee 2, and Working Group 2, and carried out by an international task force comprising 14 government, academic, and industrial research institutions. The detailed study protocol defined the computational head and mobile phone models. The participants used different finite-difference time-domain software and independently positioned the mobile phone and head models in accordance with the protocol. The results show that when the pinna SAR is calculated separately from the head SAR, SAM produced a higher SAR in the head than the anatomically correct head models. Also the larger (adult) head produced a statistically significant higher peak SAR for both the 1- and 10-g averages than did the smaller (child) head for all conditions of frequency and position.

Dielectric properties of epoxy-dielectrics-carbon black composite for phantom materials at radio frequencies

Abstract: In order to develop new dry phantom materials that can simulate the effect of electromagnetic wave on human tissues, the dielectric properties of the phantom materials composed of dielectrics, carbon black, and epoxy resin were investigated. For dielectrics/epoxy composite, the dielectric constants increased with the content of dielectric powder and were independent of frequency at the measured frequency range. The dielectric constants and conductivity of carbon black/epoxy composite also in- creased with the carbon black, but it showed the frequency dependence that the complex dielectric constants decreased with increasing frequency. The dielectric con- stants and conductivity corresponding to human tissues could be obtained by combining the frequency dependence of carbon black/epoxy composite with the dielectric proper- ties of dielectrics/epoxy composite and by adjusting the composition ratios of carbon black, dielectrics, and epoxy. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1294 -1302, 2000

The MOBI-Kids Study Protocol: Challenges in Assessing Childhood and Adolescent Exposure to Electromagnetic Fields from Wireless Telecommunication Technologies and Possible Association with Brain Tumor Risk

Abstract: The rapid increase in mobile phone use in young people has generated concern about possible health effects of exposure to radiofrequency (RF), extremely low frequency (ELF) electromagnetic fields (EMF). MOBI-Kids, a multinational case-control study, investigates the potential effects of childhood and adolescent exposure to EMF from mobile communications technologies on brain tumor risk in 14 countries. The study, which aims to include approximately 1,000 brain tumor cases aged 10-24 years and two individually matched controls for each case, follows a common protocol and builds upon the methodological experience of the INTERPHONE study. The design and conduct of a study on EMF exposure and brain tumor risk in young people in a large number of countries is complex and poses methodological challenges. This manuscript discusses the design of MOBI-Kids and describes the challenges and approaches chosen to address them, including: 1) the choice of controls operated for suspected appendicitis, to reduce potential selection bias related to low response rates among population controls; 2) investigating a young study population spanning a relatively wide age-range. 3) conducting a large, multinational epidemiological study, while adhering to increasingly stricter ethics requirements; 4) investigating a rare and potentially fatal disease; and 5) assessing exposure to EMF from communication technologies. Our experience thus far developing and implementing the study protocol indicates that MOBI-Kids is feasible and will generate results that will contribute to the understanding of potential brain tumor risks associated with use of mobile phones and other wireless communications technologies among young people.

Development of Korean Male Body Model for Computational Dosimetry

Abstract: The dimensions of the human body vary by age, sex, and race. The internal structure and outer dimensions of a body exposed to an electromagnetic field is important for accurate dosimetry. The average physical size of Korean adult males between the ages 18 to 24 was investigated, and a male volunteer was selected whose physical condition is within the physical standards, ± 5%. Magnetic resonance images and partially computerized tomography images of the volunteer were acquired. The intervals between the transverse images were 1 mm for the head and 3 mm for the rest of the body. About 30 different tissues were manually classified by an anatomist on the raw images, and the segmented images were implemented in the form of a text file appropriate for numerical formulation. model is needed to consider accurate dosimetry in a Korean human body for electromagnetic field exposures. In this letter, the development process of a voxel-based human body model and its results are described. A volunteer was selected based on the average physique of Korean males, and his body was imaged from the crown of the head to the tip of his toes using magnetic resonance (MR) imaging and computerized tomography (CT) scans. For these two types of images, an MR machine (GE Signa Horizon 1.5 Tesla MRI System) and CT machine (GE High Speed Advantage) were used. The CT scans were performed only in a partial head region for better identification of bone, fibrous tissue, and interior air. Based on these images, a three-dimensional anatomical data set suitable for numerical analysis in a rectangular grid, such as the FDTD technique, was implemented.

EMF Levels in 5G New Radio Environment in Seoul, Korea

Abstract: This paper reports the electromagnetic field (EMF) exposure levels from fifth generation (5G) services. Three mobile operators in South Korea launched the world’s first 5G New Radio networks using the 3.5 GHz band in April 2019. The transmitted power of the uplink slots and the synchronization signal reference signal received power (SS-RSRP) from user equipment (UE) were measured in Seoul. The power samples, averaged over a 1-s duration, were obtained for a traffic period of approximately 270 h from October 2019 to early February 2020 using the file transfer protocol while driving along the side streets in residential areas of Seoul. The measurement results show that the time-average level when exposed to a beam sweep of the base stations was less than $5~\mu \text{W} / \text{m}^{2}$ . However, the UE transmitted power level approached the maximum for a considerable period of the total measurement time owing to the extremely low SS-RSRP level of the base stations.

The Virtual Family—development of surface-based anatomical models of two adults and two children for dosimetric simulations

Abstract: The objective of this study was to develop anatomically correct whole body human models of an adult male (34 years old), an adult female (26 years old) and two children (an 11-year-old girl and a six-year-old boy) for the optimized evaluation of electromagnetic exposure. These four models are referred to as the Virtual Family. They are based on high resolution magnetic resonance (MR) images of healthy volunteers. More than 80 different tissue types were distinguished during the segmentation. To improve the accuracy and the effectiveness of the segmentation, a novel semi-automated tool was used to analyze and segment the data. All tissues and organs were reconstructed as three-dimensional (3D) unstructured triangulated surface objects, yielding high precision images of individual features of the body. This greatly enhances the meshing flexibility and the accuracy with respect to thin tissue layers and small organs in comparison with the traditional voxel-based representation of anatomical models. Conformal computational techniques were also applied. The techniques and tools developed in this study can be used to more effectively develop future models and further improve the accuracy of the models for various applications. For research purposes, the four models are provided for free to the scientific community.

Synopsis of IEEE Std C95.1™-2019 “IEEE Standard for Safety Levels With Respect to Human Exposure to Electric, Magnetic, and Electromagnetic Fields, 0 Hz to 300 GHz”

Abstract: The newly released IEEE Std C95.1™-2019 defines exposure criteria and associated limits for the protection of persons against established adverse health effects from exposures to electric, magnetic, and electromagnetic fields, in the frequency range 0 Hz to 300 GHz. The exposure limits apply to persons permitted in restricted environments and to the general public in unrestricted environments. These limits are not intended to apply to the exposure of patients by or under the direction of physicians and care professionals, as well as to the exposure of informed volunteers in scientific research studies, or to the use of medical devices or implants. IEEE Std C95.1™-2019 can be obtained at no cost from the IEEE Get Program https://ieeexplore.ieee.org/document/8859679.